This proposal describes a novel microcatheter intended to facilitate coronary and neurovascular diagnosis and therapy. A novel design and manufacturing method is envisioned, one that can improve microcatheter performance, and lower cost. The invention described here can be used to facilitate crossing lesions, intraarterial thrombolysis, flow measurements, and other uses. Unlike conventional microcatheters, it will also permit angioscopy. The proposed microcatheter differs from conventional microcatheters because its body will be a metal tube in which grooves approximately 0.08 mm width are cut around its circumference. The appropriate pattern of grooves imparts flexibility to the catheter, while the remaining metal provides excellent torque transmission and burst strength. A hydrogel coating on the outside will promote lubrication. This invention will improve the design and simplify the manufacture of microcatheters. Conventional microcatheters are assembled in a labor- intensive way, and contain joints that predispose the device to kinking. Kink-resistance is normally obtained by thickening the catheter wall, reducing the working channel diameter. The new design is less prone to kink than conventional microcatheters, and yields a larger working lumen. It makes possible a flexibility pattern which can be continuously varied along the catheter's length, also improving performance. Its relative suitability for automated manufacture should help reduce health care costs. PROPOSED COMMERCIAL APPLICATION: NOT AVAILABLE